Non Magnetic MRI Conditional External Defibrillator with Reduced Skeletal Muscle Contraction

Delays in defibrillation reduce survival from cardiac arrests due to ventricular fibrillation (VF). Delays in defibrillation of MRI patients occur due to the need for removal of the patient from the scanner, placement onto an MRI safe stretcher, and relocation to a nearby environment containing a defibrillator. Current defibrillators cannot be near the scanner since the MRI magnet can draw the defibrillator into the scanner, which can cause serious injuries or death. Defibrillation can be further delayed since defibrillation of MRI patients is typically performed by code teams that respond from other, often distant, locations, rather than MRI staff. Each minute in delay to defibrillation can reduce survival by 10-12%. The unmet clinical need, therefore, is the lack of availability of a system that would allow defibrillation next to or in the MRI scanner, thereby minimizing delays. The consequences of adverse outcomes from cardiac arrest in MRI scanners are catastrophic, requiring reducing risks as much as possible, by the availability of immediate MRI safe defibrillation. These delays are especially problematic since cardiac arrest from VF can complicate anesthesia administration, which is used in many of the over 45 million MRI scans done yearly in the United States. Even with modern methods, cardiac arrest can still occur during anesthesia management, with mortality as high as 30%. In addition to anesthesia- based procedures, there are a number of MRI-guided interventions with an increased risk of VF. There are also MRI-guided interventions not currently being performed, such as ablation of ventricular tachycardia, because of the high risk of VF, and the lack of the availability of immediate defibrillation. Cardiac arrest can also occur during routine MRI scans without anesthesia. The central hypothesis is that a defibrillator can be developed that would allow defibrillation in the MRI scanner, reducing delays, and allowing procedures with a higher arrhythmia risk to be done under MRI guidance. Defibrillation can be done in the scanner because of the MRI compatible properties of the system, and because motion of the patient caused by the shock is substantially reduced by a pre-shock, ramped High Frequency Alternating Current (rHFAC) waveform that reduces substantially the shock-induced skeletal muscle contraction, avoiding the patient “jumping” into the scanner bore walls. The overall objective of this proposal is to develop a clinical grade, MRI conditional defibrillator with the rHFAC waveform for submission to FDA for 510(k) clearance, which FDA has already indicated is acceptable. The Phase I objectives have been achieved. In addition, Coram has negotiated an exclusive license from Johns Hopkins University for an MRI conditional defibrillator with the rHFAC waveform, and has filed a patent on using non-magnetic transformers to improve performance. The Specific Aims are: 1) To develop a clinical grade, MRI conditional external defibrillator with the rHFAC waveform; 2) To perform verification and validation testing; and 3) To determine the optimal workflow for defibrillation in the MRI scanner. If successful, this system could become a “must have” for any MRI scanner with monitoring equipment, which represents half of the over 14,000 MRI scanners in the United States. ** This section contains proprietary information